require 'timeout'
require 'socket'
include Socket::Constants

def traceroute(destination)
  begin
    dest_address = IPSocket.getaddress(destination)
  rescue Exception => e
    puts "Can not resolve #{dest}"
    puts e.message
    return
  end

  port = 33434
  ttl  = 1
  max_hops = 30

  while true
    recv_socket = Socket.new(Socket::AF_INET, Socket::SOCK_RAW, Socket::IPPROTO_ICMP)
    recv_socket.bind(Socket.pack_sockaddr_in(port, ""))

    send_socket = Socket.new(Socket::AF_INET, Socket::SOCK_DGRAM, Socket::IPPROTO_UDP)
    send_socket.setsockopt(0, Socket::IP_TTL, ttl)
    send_socket.connect(Socket.pack_sockaddr_in(port, destination))
    send_socket.puts ""

    curr_addr = nil
    curr_name = nil

    begin
      Timeout.timeout(1) {
        data, sender = recv_socket.recvfrom 8192
        curr_addr = Socket.unpack_sockaddr_in(sender)[1].to_s
      }

      begin
        curr_name = Socket.getaddrinfo(curr_addr, 0, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)[0][2]
      rescue SocketError => e
        curr_name = curr_addr
      end

      if curr_name.empty?
        curr_host = "*"
      else
        curr_host = "#{curr_name} (#{curr_addr})"
      end
      puts "#{ttl}\t#{curr_host}"

      if curr_addr == dest_address or ttl > max_hops
        break
      end
    rescue Timeout::Error
      puts "#{ttl}\t*"
    ensure
      recv_socket.close
      send_socket.close
    end

    ttl = ttl + 1
  end
end

traceroute("google.com")